Numerous substance-abuse preventive intervention programs have now reached the standard of being evidence-based interventions (EBIs) by demonstrating overall effectiveness for those who enroll (Catalano et al., 2012; Kumpfer & Alvarado, 2003). However, as indicated by variation in effects, some participants benefit from these EBIs more than others. At this stage of evidence, more research is needed to explain how EBIs work and for whom (Kazdin, 2004; Sandler et al., 2011). Specifically, the process of change during implementation of EBIs is largely a mystery (Kazdin, 2007). To strengthen research on EBI-induced change, this work will focus on the process of change in a family-based intervention (SFP: 10-14) and will include examination of (1) weekly engagement in program sessions as a moderator of the heterogeneity in change, (2) the process of change in functioning, using intensive longitudinal data to assess weekly parenting/family processes, and (3) associating these processes of change to traditional baseline to post-test measures to examine which patterns of change are optimal. This research will pave the way for future investigation into program effects using daily data collection, which is particularly suited to the evaluation of mechanisms of change (Mehl & Conner, 2012) and will inform promising avenues to bolster the effects of EBIs. This work will provide me with the opportunity to focus on my research and training goals as I prepare for a career as an independent investigator.